package demo1;

public class BinaryTree {
    static class TreeNode{
        public char val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(char val) {
            this.val = val;
        }
    }
         TreeNode root;
    public void createTree(){
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');
        A.left = B;
        A.right = C;
        B.left = D;
        B.right = E;
        C.left = F;
        C.right = G;
        E.right = H;
        this.root= A;
    }
    //前序遍历
    public void preOrde(TreeNode root){
        if(root == null){
            return;
        }
        System.out.print(root.val  + " ");
        preOrde(root.left);
        preOrde(root.right);
        return;
    }
    //中序遍历
    public void inOrder(TreeNode root){
        if(root == null){
            return;
        }
        inOrder(root.left);
        System.out.print(root.val +  " ");
        inOrder(root.right);
    }
    //后序遍历
    public void postOrder(TreeNode root){
        if(root == null){
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }
    //获取树中节点的个数
    int size(TreeNode root){
        if(root == null){
            return 0;
        }
        return size(root.left) + size(root.right) + 1;
     }
    //获取叶⼦节点的个数
    int getLeafNodeCount(TreeNode root){
        if(root == null){
            return 0;
        }
        if(root.left == null && root.right == null){
            return 1;
        }
        return getLeafNodeCount(root.left) + getLeafNodeCount(root.right);
    }
    //获取第 K 层节点的个数
    int getKLevelNodeCount(TreeNode root,int k){
        if(root == null){
            return 0;
        }
        if(k == 1){
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1) + getKLevelNodeCount(root.right,k-1);
    }
    //获取⼆叉树的⾼度
    int getHeight(TreeNode root){
        if(root == null){
            return 0;
        }
        int leftHeight = getHeight(root.left);
        int rightHeight = getHeight(root.right);
        return Math.max(leftHeight,rightHeight) + 1;
    }
    //检测值为 value 的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if (root == null) {
            return null;
        }
        if (root.val == val) {
            return root;
        }
        find(root.left, val);
        find(root.right, val);
        return null;
    }

}
